Most guys that shoot Glocks in Open Class are running 9 Major Comp'd G17's. I'm sure you could build it up & still compete, you'll just have to do a TON of load development/spring calibration to get a comparably flat shooting 10mm round. Another member here, Boba Debt, built an open gun out of a G20LS.
GEN 3 20LS/20SF/21SF/30SF/23/34/26
GEN 4 17/19/21/34/35